土壤甲烷氧化菌及水分状况对其活性的影响

Mechanism of methane oxidation by methanotrophs and effect of soil moisture content on their activity

  • 摘要: 阐述了土壤中甲皖氧化的机理及土壤水分状况对甲烷氧化的影响,土壤中甲烷氧化分4步进行,首先甲烷在sMMO 或pMMO作用下氧化成甲醇,甲醇在甲醇脱氢酶作用下氧化成甲醛,甲醛是甲垸氧化菌合成体细胞的碳源,甲烷氧化菌Type I利用RuMP途径把甲醛转化为细胞合成的中间体,TypeⅡ则利用丝氨酸途径,同时甲醛在甲醛脱氢酶作用下氧化为甲酸,后者再在甲酸脱氢酶作用下氧化为CO2,从而完成甲垸氧化。甲烷氧化菌Type 1只含pMMO,而Type 1I既含sMMO又含pMMO,因此其生存力更强。土壤中甲烷氧化主要发生在10cm 左右的土层中,明显受土壤水分状况的影响,甲烷氧化的最佳土壤含水量变化为20%~70%问,主要取决于土壤机械组成和有机质含量。

     

    Abstract: The paper reviews the mechanism of methane oxidation by methanotrophs in soils and influence of soil moisture content on methanotrophic function.Four steps are included in the process of methane oxidation in soils.Methane is first oxidized to methanol by sMMO or pMMO and then the latter is further transformed into formaldehyde by methanol dehydrogenase,which is the carbon source of methanotrophic cell syntheses and can be assimilated through RuMP pathway and serine pathway by Type I and Type II methanotrophs,respectively.Type II methanotroph contains both sMMO and pMMO but Type I only pMMO.so Type II methanotroph can survive better in environments where nutrients such as nitrogen,copper are limited.The maximum rate of methane oxidation by methanotroph exists in soil subsurfaces and is mostly influenced by soil moisture content,which is,in turn,mainly dependent on soil texture,soll organic matter and so on.

     

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